Investigation of saliva collection and a sensitive HPLC assay for assessment homocysteine status is proposed. The current technology for assessing homocysteine status, measurement of plasma homocysteine concentration, is confounded by preanalytical contamination of plasma with homocysteine released from red blood cells before sample processing. The elaborate specimen handling necessary to prevent this is frequently not achievable in actual practice. However, it may be avoided by measurement of homocysteine in saliva by a sensitive HPLC-procedure. The additional advantages of salivary analyte tests are that they are non- invasive, convenient and avoid costly phlebotomy. Preliminary results from this laboratory indicate that homocysteine rapidly disappears from fresh whole saliva, perhaps because of the well-documented presence of thiol degrading bacteria in saliva. This problem can be overcome by using inhibitors of salivary homocysteine degradation that we have discovered. We intend to exploit our preliminary findings by elaborating a saliva collection system that employs inhibitors of homocysteine breakdown, and saliva collection in a specially designed SalivaSac(R) device (a patented device used to collect a salivary ultrafiltrate) that is impermeable to bacteria, and other particulates, but not to proteins. PROPOSED COMMERCIAL APPLICATIONS: The need for screening homocysteine status is potentially enormous. A serious obstacle to assessment of homocysteine status has been the confounding of results by preanalytical contamination of the plasma with red blood cell-derived homocysteine. The elaborate specimen handling necessary is frequently not achievable in actual practice. Salivary homocysteine measurement will avoid this problem. In addition, measurement of salivary analytes is non-invasive, convenient and avoids costly phlebotomy.